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Explain how the given type of rock is formed
Gneiss

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Gneiss is a type of metamorphic rock that is created under intense pressure and heat. It is usually formed at convergent plate boundaries, or in regions where the rock is heated to temperatures greater than 500 degrees Celsius and pressure exceeds 15,000 pounds per square inch. Gneiss is often made up of alternating light and dark colored bands of minerals, which indicate changes in the composition and density of the surrounding rock during heat and pressure.